1. Field of the Invention
The present invention generally relates to a rotary electric machine such as an alternating current generator for vehicles and, more particularly, to a cooling mechanism of such a rotary electric machine.
2. Description of Related Art
As an example of conventional rotary electric machines, Japanese Unexamined Patent Publication No. 3-178539 discloses an alternating current generator as illustrated in FIG. 8. This alternating current generator includes a housing 100 with a plurality of cooling windows w formed in a cylindrical peripheral wall and circumferentially aligned in a row, and a centrifugal fan 106 positioned inside the cooling windows w and fixed to the end of a rotor (not illustrated) in the housing 100. The peripheral wall of the housing 100 has guide wall parts 102, each of which is positioned between circumferentially adjacent ones of the cooling windows w and axially extends therebetween. Each guide wall part 102 is inclined at a constant angle .theta. against the radial direction, so that the cooling wind blown out of the cooling windows w is blown out in this inclined direction. Between the two cooling windows w circumferentially adjacent to each other axially extends support parts 103 and the circumferential width of each support part 103 is made to be wider than the circumferential width of the guide wall part 102.
In the above conventional rotary electric machine, the support parts 103 result in large fluid resistances against cooling wind generated by the centrifugal fan 106, causing increase in fluid loss, decrease in cooling ability or increase in whizzing sound.